Cushioning valve



' g- 1942- 'r. L. FARNHAM 1 2,292,336

. CUSHIONING VALVE Filed Dec. 15, 1939 4 Sheets-Sheet 3 Inventor n/vaa as 4, Fem/rd? Mfm Rttornzys Patented Aug. 4,1942

UNITED STATES PATENT OFFICE.

CUSHIONING VALVE Thaddeus L. Farnham, Pittsburgh, Pa., assignor to The Hydraulic Development Corp. Inc., Wilmington, Del., a corporation of Delaware Application December 15, 1939, Serial No. 309,453 16 Claims. (Cl. 121-44) supports which are not very rigid. An example is a-hydraulic motor which is employed in connection with an electric melting furnace where the heavy carbon electrodes are mounted in the furnace cover. For charging such a furnace, it is necessary to lift the cover clear of the furnace top and to rotate it'at high speed to one side so that a fresh charge can be placed in the furnace from above. As the electrodes are long and heavy and are easily broken if caused to vibrate, it is necessary that the furnace cover after being lifted clear of the furnace and rotated out of the way at high speed be brought to rest without perceptible shock at an point since vibration of the cover will cause breakage of the electrodes which are very expensive and troublesome to replace and since other parts of the equipment might also be damaged. After the loading of the furnace, the cover must be rapidly swung into exact position over the furnace, being stopped in this position without perceptible jar, and lowered onto the furnace. Itwill be seen that the operation calls for the use of considerable power, that the cover is moved at high speed, and that stopping of the'motion of the cover must be performed without shock .or vibration.

The present invention provides for the cushioning of the hydraulic ram which rotates the cover at either. end of the movement thereof. ,While the invention is described herein with reference to a hydraulic motor whereby a mass is rotated, it will be understood that it is applicable to any hydraulic ram for cushioning of the stopping thereof in either direction, regardless of the function which is performed by the ram. Likewise, while the invention is described with reference to a double-acting hydraulic ram, it will be obvi-.

ous that it may be applied to only one end of the ram where cushioning in only one direction is desired, or that it may be applied to a singleacting hydraulic ram wherein, for example, the return stroke is accomplished by the influence of gravity.

It is an object of the present invention to provide a cushioning or decelerating device for a hydraulic ram which is adapt d. to bri g th hydraulic ram to rest at the desired limit of motion thereof without appreciable shock.

It is another object to provide a positive stop for the ram at the proper point; in a preferred embodiment, the invention provides for adjustment of the point of stopping the ram so as to.

substantially coincide with the point where the positive stop is engaged after assembly of the ram with the mechanism which it moves.

Another object is to provide mechanism in which the moving mass is brought to rest by the throttling of the outlet-ofthe hydraulic medium from the discharge side of the ram; in a preferred form the device permits for the free discharge of hydraulic medium and full speed of the ram until the point of retardation is reached, and at the point of retardation the device so restricts the opening for the hydraulic medium as to gradually build up the retarding pressure to the desired point and thereafter by progressive further restriction maintains a constant retarding pressure or effort in spite of the decreased speed of ram movement; the ram is finally brought to rest exactly at the positive stop point, provision being made for the quick and easy adjustment of the point at which the ram is tfinally brought to-rest as conditions change from time to time. I

Another object is to provide a device of the foregoing type wherein the hydraulic fluid freely enters on the forward stroke of the ram and at the same time on the exhaust stroke, the outflow is entirely under the control of the throttling device with a minimum amount of leakage at any point; it is preferred to employ a combination valve and throttling rod which is a piston valve positively operated by hydraulic pressure and is capable of shearing ofi any bits of packing or the like which might lodge in its ports and which would prevent closure of a check valve or a positively seated poppet valve.

Another object is to prov1de a mechanism of the foregoing type wherein the valve and cushion rod may move freely without binding in spite of slight misalignment thereof and still maintain a close valving fit both in the moving piston and inthe cylinder head; in a preferred form .this is accomplished by the employment of a floating packing such as a floating ring around the valve rod at a suitable point on the length thereof.

Still other objects will more fully hereinafter appear as the description of the embodiment of the invention portrayed in the drawings proceeds. In the accompanying drawings;

F g, 1 s a s de e evat o of t e ift n y nder 2 and an end view of the rotating cylinder which is equipped with a cushioning device embodying the present invention.

Fig. 2 is a vertical sectional view taken on the line 2-2 of Fig. 1 looking in the direction of the arrows.

Fig. 3 is a horizontal sectional view on the line Fig. 6 is a detailed sectional view on the line 5-5 of Fig. 5.

Fig. '7 is a transverse sectional view on the line 1--1 of Fig. 5.

Fig. 8 is a transverse section on the line 88 of Fig. 5.

Figs. 9 to 12 are sectional views of modified forms of cushioning devices.

Referring to the drawings in detail, the-casing of the vertical lifting cylinder is designated as "I. Casing I9 has formed thereon integral flanges II for attachment'of the device to any suitable support such as the wall of the electric furnace with which the device is employed. The casing I0 is generally cylindrical and contains the lifting ram l2 which is guided in bushings l3 and I4. Gland I5 compresses packing Hi to prevent leakage along the ram I2.

l1 which forms pressure cavity,|8. Cast integral with the internal surface of cylinder head I1 is key. l9 which is received within a keyway 29 formed in the lower end of ram |2. This key l9 serves to position the ram l2 and to thereby pre- The lower- 'end of the casing I9 is closed by cylinder head vent rotation of ram |-2 during the operation of moving the ram up or down, thereby insuring alignment of the furnace cover carried by the ram l2 with the furnace as it is raised or lowered at the beginning of its removal or at the end of its replacement. Key l9 and keyway 20 are located at any desired angular positionrelatlve to ram 2. For example, they may be so located that key I9 is in the dotted line position shown in Fig.2. The upward movement of the ram I2 is limited by the engagement-of ring 2| carried by the ram l2 in any suitable manner with the shoulder 22 of the casing l5. An annular space 23 is formed between the ram l2 and the casing l5 and oil under pressure is admitted to this sures lubrication of the ram and of the enmeshing gear teeth for rotating the ram which will be hereinafter described. In order to elevate the ram l2, oil under pressure is admitted into pressure chamber 13, a portion of this oil being admitted to space 23'when the mechanism is first placed in operation by means of passageway 24. In order to lower the ram and with it the mechanism carried thereby, the oil is allowed to discharge from space l8, whereupon the ram |2 descends under the influence of gravity. 'The furnace cover or other device to be lifted and rotated by the rams is carried on the reduced upper portion 25 of the ram I2, a recess 25 of suitable type being {provided within this portion 25 to aid in the attachment of the furnace cover or the like to the ram l2.

A gear sector 21' having vertically extending teeth is attached to ram l2 within the annular space 23 by any suitable means, as by fastening it suitably to the half collar 28a, the dowel pin 28 serving to prevent the ring 29a from turning on the ram l2. This sector 21 engages rack 29 which is attached to rotating ram 3|! which is disposed within the casing 3| mounted inter mediate casing III on one side thereof. Ram 35 operates to rotate ram l2 after ram l2 has been elevated. It will be understood that the teeth on sector 21 and on rack 29 are preferably so elongated as to remain enmeshed even when the ram I2 is in itslowermost position. The cushioning device of the present invention is applied to the rotating ram 39 and is adapted to cushion the stopping of ram 30 at the ends of its travel. Rotating ram 39 has piston heads 32 and 33 operating in cylinders 34 and 35 respectively, which are attached to casing 3| in any suitable manner.

-Ram 30 has an axial bore within which is reciprocably disposed the cushioning valve rod 35 which extends through the ram 39 and beyond the ends of piston heads 32 and 33. The ends of rod 35 extend slidably through extremely close fitting guides 31 and 38 formed in the ends of cylinders 34 and 35, respectively, extending into the cavities 39 and 49 formed in the heads of cylinders 34 and 35, respectively. Fixedly carried on the outward ends of piston heads 32 and 33 are plates 4| and 42 respectively disposed, these plates surrounding the rod 35 with considerable clearance, which is comparable to the clearance existing between ram 30 and rod 35. These plates 4| and 42 are each formed with a radially extending groove 43and 44 respectively which serves to admit the pressure fluid into the pressure cavities 45 and 45 formed in cylinders 34 and 35 respectively, in a. manner which will presently appear. The plates 4| and 42 are formed with an annular abutting portion 41 and 48 respectively, which is adapted to about the inner faces 55 and 55 of the ends of cylinders 34 and 35, respectively. Plates 4| and 42 are each further provided with an annular recess within which is received floating rings 49 and 50, respectively.

Floating, rings 49 and are held in place by plates 4| and 42 and are allowed to move radially to prevent binding of valve rod 35-due to any misalignment thereof with rings 49 and 5|] and with guides 31 and 38. Rings 49 and 59 slidably engage the surface of rod 35 with an extremely close clearance, whereby the escape of pressure liquid along the rings toward the middle of rod 35 is prevented. This construction is exceedingly reliable and compact and allows the valve rod 36 to shift readily without having the seal destroyed. It will be understood that rings 49 and 55 likewise engage the surfaces of plates 4| and 42 and of piston heads 32 and 33 slidingly but with extremely closeclearance.

Valve rod 35 has axial holes 5| and 52 drilled from its right hand and left hand ends, respectively, as viewed in Fig. 3, and the ends of the valve rod 35 are machined with slots 53 and 54 respectively connecting with holes 5| and 52. On theright hand end of the rod 35 towards the inward end of hole5l are four radial connecting holes 55, these connecting holes 55 being relatively large in diameter and being adapted to freely connect bore 5| with the chamber 45 in cylinder 34. The left hand end of rod 35 is i similarly provided with identical holes 55. Lo-

As ram 36 approaches the limit of its righta series of longitudinally spaced connecting holes 51 and 58 respectively, these holes 51 and 56 being progressively more closely spaced and of progressively smaller diameter as oneproceeds outwardly from holes 55 and 56. Thes holes 51 and 58 are disposed in a single row on only one side of the rod 36 instead of extending in four directions as do holes 55 and 56, and these holes 51 and 58 likewise communicate with bores and 52. v

The ends of rod 36 are adapted to abut against threaded plugs 59 and 66 which are threadably mounted in the ends of cylinders 34 and 35 rescribed below.

ward travel, the cushioning action will take place, this cushioning action being more fully de- 6 Operation I shown in Fig. 2, as key 16 will be engaged in spectively. These plugs 59 and 66 are covered by removable end caps 6| and 62 respectively, which serve to prevent unauthorized changes in the position of the threaded plugs and also serve to prevent oil leakage around the threads of the plugs.

Communicating with chambers 39 and 46 are conduits 63 and 64 respectively which are adapted to act either as'inlet or discharge conduits, depending upon in which direction ram 36 is being moved. Plugs 59 and 60 are so adjusted that whenrod 36 abuts against one of them, the slot 53 or 54 in the other end of rod 36 is adapted to freely interconnect passageway 63 or 64 and chamber 39 or 40 with pressure cavity 45 or 46', this being accomplished by having slots 53 and 54 of a length such that the slots extend into the interior of chamber 45 or 46. This is indicated at the right hand end of Fig. 3, wherein slot 53 has a considerable portion disposed within chamber'45 and hence is adapted to allow free entry of the pressure fluid from conduit 63 into the chamber 45 where it may act upon the piston head 32 of ram 30 to move the same away from the fluid inlet. When rod 36 abuts either of the plugs 59 or 60, its slot 53 or 54 is in non-communicating relationship with the pressure cavity 45 or 46, as isindicated in the left hand portion of Figure ,3, whereby when the pressure fluid is first admitted its flrst'action is to move the rod 36 axially .into engagement with the other plug 56 or 66, thisaction also serving to place'the slot 53 or 54 in communication with the chamber 45 or 46, thereby allowing the pressure fluid thence to act upon the piston head 32 or 33.

The stroke of rotating ram 36 is sufficient to produce the desired rotation. of vertical lifting ram I2. After this desired rotation has been ac- 'complished, the finished surface 41 or 46 of the plate 4| or 42 on ram 36 will be in contact with the finished surface 65 or 66 respectively on the inward surface of cylinder 34 or 35. The reverse rotation to the same extent of lifting ram l2 in the opposite direction will bring the corresponding surfaces 41 or 48 into contact with surfaces 65 or 66. Thus, Figs. 2 and 3 have been drawn with the ram 12 lifted and rotation about to commence, the surface 48 of plate 42 on the left hand end of ram 36 being in contact with the surface ram l2 by right hand movement of ram 36, the right hand surface 41 ofplate 4| will be in corresponding contact with the surface 65forme'd on the inward right hand end of cylinder 34.

, Likewise, in Fig. 3, the rod 36 is shifted leftwardly 36 rightwardly. v

keyway 26 until the ram has reached its upward position.

With the ram l2 in its upward position as m Fig. 2 and with the ram 36 in the position shown in Fig. 3, pressure will be admitted through conduit 64 at the left of Fig.- 3 to the cavity 40, whereupon valve rod 36 will be moved to the right until it contacts 'plug 59. When this movement of rod 36 has been completed, slot 54 in theleft hand end of valve rod 36 will have passed partly through the close-fitting guide 38 so that oi under pressure can pass from chamber 46 through the slot 54 into the chamber 46 in cylinder 35, thus applying pressure rightwardly upon piston head 33.

As ram 30 moves well to the right, ring 45 covers up the relatively large radial holes 55 in rod 36, thereby producing a reduction in the discharge area and a throttlingof the oil discharge from chamber 45. As ram 36 continues in its movement rightwardly, ring 43 covers .up holes in the group 51, thereby gradually still further reducingthe discharge area and still further exerting a throttling effect on the discharge of the oil. This progressive throttling effect slows up the rightward movement of ram 36 and continues until ring 49 has just covered the outwardmost hole 51, at' which point the ram 36 has substantially stopped and the face 41 is in abutting relation with the face 65 of cylinder 34.

'66 on the inward face of the-end of left hand cylinder 35. Upon completion of the rotation of In moving ram 30 leftwardly of Fig. 3, pressure fluid will be admitted to conduit 63 whereupon the reverse action will take place, this action being identical with that just described for the rightward movement of ram 36.

- The holes 55, 56, 61 and 56 are so dimensioned and so spaced that the throttling effect brings rest at precisely or substantially the the ram to moment when the surface 41 or 48 contacts the surface 65 or 66,'thereby preventing any shock or jar on ram 36 and on the parts operatively connected thereto. The operation may be adremoving caps 61 and 62 and screwthreadedly adjusting plugs 53 and 66. The rod 36 maybe easily removed and another having different throttling characteristics substituted without dismantling the machine by removing the caps 6| or 62 and the plugs 66 or .66 and withdrawing the valve rod 36. Plugs 53 and 66 may be subsequently adjusted slightly in the manner described above to provide for changes in operating conditions.

Modifications The construction shown in Fig. 9 is similar to that described above except that'the threaded justed by plug 66 is threadably carried in a removable cap plate 61 and has a head 60a against which the end of rod 36 is adapted to abut. The chamber 46 is in communication with the conduit 64 through holes 66 and 63, axial bore 62 and slots 60!) cut in the end of rod 36. The piston head 33 is formed with a close fit around rod 36. The end 01' rod 36 is received within a bore 66 in a circular member 84 integral with the end of cylinder 36. Member 84 is provided with a plurality of angularlyspaced radial bores 86 which are disposed just outwardly of the end of rod 36 when rod 36 is in its retracted position and which are sealed off by rod 36 when it abuts against the head 60a of plug 63. The end of rod 36 is provided with a plurality of snap rings 86 which cause the end of rod 36 to be tightly sealed relative to flange 84 even though axial misalignment of rod 36 relative to bore 68 exists.

In the modification of Fig. 9, the operation is as "follows. The parts are shown in Fig. 9 as they'would be with the ram and piston head 33 beginning their movement leftwardly with the rod 36 shifted so as to seal the free hydraulic connection between chamber 46 and inlet conduit 64' by way of ports 86. Upon the application of fluid pressure to the right hand end of the ram, the rod 36 was moved leftwardly by the fiuid pressure so exerted, closing off the ports 86 and compelling the exhaust from chamber 46 to take place through large ports 56 and small ports 68 and thence through axial bore 62 and slots 60!: to chamber 48. When the movement of the piston head 33 leftwardly has closed the ports 66, the discharge continues through ports 63 and the cushioning efiect is determined as before by the number, size and spacing of these ports 68.

In Fig. 10 the construction is generally similar to that shown in Figs. 3 and but the cushioning means is modified therefrom. The end of rod 36 has an axial bore 63 and is adapted to abut against a projection 10. Fixedly carried on rod 36 are an elongated sleeve II and an annular piston I2 which forms with sleeve II and piston head 33 an annular cushioning chamber 13. Chamber I3 is in communication with pressure chamber 46 by means of the axial bores 14 which are in communication with bore 63 by means of radial bores 16. One of the bores 14 is in additional communication with the chamber 46 by the spaced radial bores 16. Thus, there is a free flow of oil to and from the cushioning chamber except when the end of rod 36 is seated against the cylinder head abutment 16. With this design, pressure applied to the other end of the double-acting ram would immediately place the cushioning piston 12 in the cushioning position as in Fig. 10, cushioning space 13 being thus filled with oil by. reason of the suction created by this movement of the end of rod 36 outwardly away from piston head 33. The piston 12 and the ram would then move as a unit until the rod 36 contacted the abutment 10, closing orifice 63 and causing a cushioning action by reason of the limited discharge area of ports". successively, these ports I6 would be cut on by the continued movement of the ram and of piston 33 relative to piston 12, thus exerting a throttling action and bringing the ram and piston head 33 to a stop at the desired position. This construction does not have the advantages of the construction shown in Figs. 3 and 5, since there is a possibility of not makings. tight seat between the end of the rod 36 and the abutment", and the possibility of I the rod being held 01! of its seat 13 by any foreign substance such as apiece of packing which might get into the cylinder. I

In the modification shown in Fig. 11, the oil underpressure is admitted through conduit 64 which is located in a cap 11 which has anaxial bore 16 and which is separated from the end of cylinder 36 by a fiber washer 13, the inner annular portion of which extends inwardly of the coaxial bore 83 in the end of cylinder 36. The rod 36 is formed in two pieces, the joint being indicated at, in order to facilitate-assembly. The outward end of the left rod half 36 is enlarged at 82, this enlarged portion being received between radial guide vanes 83 which guide it into the bore 36 and into engagement with the fiber washer 13. The rod 36 has an end bore 62 as before and radial discharge orifices 66 and 68. When pressure is applied to the opposite end of the ram, that pressure first acts upon rod 36 to move its head 82 into seating engagement wtih fiber washer 13, thereby closing ofl the direct passage from conduit 64 and bore 18 into the pressure chamber 46. The ram piston head 33 will then be moved leftwardly, causing the oil in chamber 46 to be discharged into conduit 64 through orifices 66 and 68. As soon as the piston head 33 closes the large orifices 66, the discharge of oil from the cylinder is confined to the small orifices 66 and the cushioning eiTect is controlled by the number, size and spacing of these orifices 66. The use of the large diameter head 82 is for the purpose of insuring that when the end of head 62 is once seated against washer 13, there will be a differential in area between this head 82 and the rod 36 so that as the cushioning pressure increases, it will force this head against the fiber seat 13 still more forcibly. I

In themodification shown in Fig. 12, the rod 36 is dispensed with and a member 81 is fixedly mounted in the end of cylinder 36 in any suitspace 46 where it is formed with a slightly tapered portion 38 and a more tapered portion 63. This radial bores 32. Conduit 3| is adapted to be placed member 61 is hollow, being provided with an axial bore 36 which is in communication with the inlet conduit 64 and with a conduit 3| by means of into communication with a conduit 33 which leads to the pressure chamber 46, by the opening of a spring pressed check valve 34 upon the admission of fluid under pressure to conduit 64 with piston head 33 in its extreme leftward position. I The piston head 33 is provided with an inserted member 36 which has an'axial bore 36 in line with a similar bore 31 in the piston head 33. Thus, with the parts as in Fig. 12, if pressure is applied at the right hand end (not shown) of ram 36, the liquid in chamber 46 is forced outwardly, causing check valve 34 to close 'very tightly, whereby the liquid is compelled to make its exit through bore 33. As the piston head 33 moves leftwardly, its bores 36 and 31 accommodate the inwardly projecting end of member 61, gradually restricting the outletarea by reason of the tapers 63 and 86 being received within the bores 36v and 31 until the ram 33 is brought to a stop with the surface 36 of piston head 36 abutting against the inward surface 33 of the head of cylinder 36, the 4 sure medium will be admitted through bore 90 and check valve 94 may close partially or.completely under the action of its spring. 1

From the foregoing, it will be seen that the present invention provides an unusually efiective method of bringing a hydraulic ram or the like to rest without shock or Jar. The construction is not unduly complex and is adapted to operate over long periods without the necessity for main- .tenance.- Accordingly, the present invention is highly advantageous and is-desirably used whenever it is desired to bring a hydraulic ram or the like to rest without appreciable shock or vibration.

The device as illustrated permits an adjustment of the positive point of stop of the ram 30 by machining or turning down the surfaces 4'! and 48 on the members 4| and 42. This provides an initial adjustment which may be taken care of by the erector when assembling the device. This turning down adjusts the relationship of the piston, the ram and the rack at the end of the stroke making them closer to the surfaces-65 and 65. The theory of operation may be stated otherwise than that implied above, as follows: refer-1 ring to Fig. 3, when the ring 49 starts to close the holes 55, decelerating pressure begins to appear in chamber 45. Theoretically this pressure should rise to the maximum desired very quickly .and thereafter the arrangement and size of the additional holes 5| should be such as to maintain, as nearly as possible, a uniform pressure in chamber 45 in spite of the fact that the movement of the ram 30 is continually growing slower and the flow of oil is thereafter continually less. This produces, theoretically, a constant and uniform deceleration of the'ram 30 and in practice this theoretical result isclosely'approached.

Instead of employing a series of holes there might be employed a slot or other type of passage in the valve rod 36 which passage would be gradually closed in the same way as the series of holes shown. In fact, if a slot or a series of slots or a groove or a series of grooves is provided, the size of the passageway for the oil could be made at each point theoretically correct. An additional advantage of the use of a slot or groove or a plurality thereof is that it is much easier to accurately designate on a drawing and to accurately duplicate in successive constructions.

I wish it to be understood that I intend to include as within my invention such modifications as may be necessary to adapt the same to varying conditions and uses and as fall within the terms or the spirit of the' appended claims.

Having thus fully described my invention,'what I claim as new and desire to secure by Letters Patent is:

1. A cushioning device for decelerating a moving member in one direction of movement comprising means formirig a chamber adapted to receive fluid, means forming a fluid operable pistonoperating in said chamber, one ofsaid means being operatively connected to said moving memher so as to move together with said moving member relative to the other of said means to expel fluid from said chamber when said moving member moves in said direction, means carried by said piston forming a bore parallel to the axis thereof, and means projecting into said chamber parallel to the axis thereof and adapted to move in said bore of said piston, said lastnamed meanshaving a longitudinal outlet bore therein and being adapted to cooperate with said means carried by said piston toprog'ressively increasingly throttle the discharge of fluid from said chamber through said outlet bore as said member moves in said direction and to thereby decelerate said moving member.

2. A cushioning device for decelerating a moving member in one direction of movement thereof comprising means forming ahydraulic chamber, means forming a hydraulic piston operating therein, a hydraulic medium in said chamber, an

outlet for said chamber, one of said means being operatively connected to said moving member so asto move together with said moving member when said moving member moves in said direction of movement and to expel said medium from said chamber through said outlet, means on said piston forming a bore parallel to the axis thereof,

chamber and adapted to reciprocate in said bore, said means forming a projection having a longitudinal bore in communication with said outlet and having a plurality of longitudinally spaced transverse bores extending from said longitudinal bore to the surface of said projection,- said piston successively sealing said transverse bores. as said member moves in said direction and thereby progressively increasing throttling the expulsion of said medium from said chamber and decelerating said moving member.

3. A cushioning device for decelerating the movement of a moving member in one direction comprising a chamber adapted to receive fluid,

means forming an inlet and outlet for said chamber extending through'said piston and having a longitudinal outlet bore in communication with said outlet and a plurality of longitudinally spaced transverse bores adapted to connect said chamber to said outlet bore and to be progressively sealed off by the advance of said piston as said moving member moves in said direction, to thereby progressively increasingly throttle the discharge of fluid from said chamber and decelerate said moving member, means for freely connecting said inlet to said chamber when said reciprocable member is moved in one direction, .and means for sealing said last-named means when said reciprocable member is moved in the opposite direction.

4. A cushioning device for decelerating the movement of a hydraulic ram comprising a hydraulic cylinder by receiving said ram, means on the head of said cylinder forming a bore parallel to the axis thereof, a reciprocable rod tightly but slidably mounted in said bore and extending through said chamber and into said ram, means on said ram for tightly but slidably engaging said rod, means on said cylinder head forming a stop dium from said cylinder.

in the end of said rod which is adapted when said rod is moved away from said stop to place said conduit in free communication with said chamber and which is out of such communication when said'rod engages said stop, a longitudinal bore in said rod, a plurality of longitudinally spaced transverse bores in said rod extending from said longitudinal bore to the surface thereof, said transverse bores being located in the chamber portion of said rod and being adapted to be progressively sealed as said piston moves toward the head of said cylinder.

5. In a cushioning device, a hydraulic, piston, a hydraulic cylinder in which said piston is reciprocable, a hydraulic medium in said cylinder, means associated with said cylinder for receiving said medium from the interior of said cylinder, reciprocable controlling means having longitudinally extending outlet means associated with said cylinder and-in communication with said receiving means for conducting said medium from the interior of said cylinder to said receiving'means, and means carried by said piston and .movablerelative to said controlling means for progressively covering said outlet means as said cylinder and said piston move relatively towards one another and for thereby progressively in-.

creasingly' throttling the discharge of said me- .6. In a cushioning device, a member to' be cushioned, means forming a cushioning space, a

hydraulic medium in said space, outlet means leading from said space for conducting said medium therefrom, expelling means operatively connected with said member to be cushioned for expelling said medium from said space through said outlet means, and a control member adapted in response to fluid pressure acting thereupon sequentially to initiate movement of said exmerit of said rod, said free communication being adapted to besealed by movement of said rod towards the said conduit means, and longitudinally extending discharge-means on each e'id of said rod between said recess and the adjacent end of said ram and adapted to be progressively covered up by saidram as it is moved towards the adjacent recess,

9. In a fluid operable motor, a double-acting therebyadmit pressure fluid to move said ram in a direction away from the established free communication, longitudinally extending discharge means -on each end of said rod between said recess and the adjacent end ofsaid ram and adapted to be progressivelycovered up by said ram as it is moved towards the adjacent recess,

and means carried by each ofsaid cylinders for adjusting the limit of endwise travel of said rod towards said cylinder.

10. In a fluid operable motor, a double-acting I fluid operable ram, a cylinder at each end thereof for receiving said ram, conduit means associated with each of said cylinders and adapted alternately to be supplied with pressure fluid, a

valve member slidably mounted in said ram and member communicating'with the adjacent conduit means and adapted to be progressively covered up by said ram as it is moved towards the respective discharge means for gradually slowingv with each of said cylinders for freely conducting pressure fluid alternatively to the interior of said cylinders, outlet means associated with each of said cylinders for conducting said fluid from the interior thereof, and a control member movable independently of said ram and having means operated by said ram for progressively diminishing the effective area of said outlet means as said ram moves-towards the cylinder with-which said outlet means is associated, said control member automatically cutting of! direct communication between said inlet means and the adjacent cylinder in response to a predeterminedfluid pressure in the other cylinder.

v8. In a fluid operable motor, a double-acting.

, adjacent said recess to thereby admit pressure fluid to move said ram in the direction of movedown said ram.

11. In a fluid operable motor, a double-acting fluid operable ram, a cylinder at each end thereof for' receiving said ram,'conduit means associated with each oi! said cylinders and adapted alternately. to be supplied with pressure' fluid, a rod slidably mounted in said ram parallel to the axis thereof. said rod extending into said conduit eans recessin each end of said rod adapted when being moved in a direction away fromits adjacent conduit means to place said conduit means in free communication with the adjacent cylinder to admit pressure fluid for moving said ram in the direction of movement of said rod, axially extending discharge means provided on each end of said rod and communicating with the adjacent recess in said rod and adapted to communicate with the adjacent cylinder by transverse bores in said rod.

12. In combinatioma cylinder having a port at each end thereof adaptedselectively to admit fluid to one end thereof and to exhaust fluid from the other endand vice versa, a fluid operable piston reciprocably mounted in said cylinder and having opposed piston areas adjacent the ends of said cylinder, a rod reciprocably mounted in said piston and having means for selectively ef'fecting unrestricted hydraulic communication between one cylinder end and its adjacent port and also being provided with metering ports and a passageway for selectively efiecting restricted hydraulic communicationbetween one cylinder end and its adjacent port, said metering ports decreasing in diameter toward the adjacent end of said rod and being arranged so as to be progressively closed by said piston when the latter I ment of said reciprocable member.

moves toward the other end of said rod, and

means associated with said rod and responsive to the supply of pressure fluid through one of said ports to shift said rod. to interrupt unrestricted hydraulic communication between the other port and the adjacent cylinder end, while establishing hydraulic communication between said first port and the adjacent piston to cause a stroke of said piston.

13. In combination, a cylinder having ports at each end thereof for alternately admitting and exhausting fluid, a reciprocably mounted rod having metering ports and passageways in either end thereof, a fluid operable reciprocable piston mounted on said rod adapted to freely reciprocate thereon and within said cylinder, said piston being so arranged as to progressively cover said metering ports at either end of 'said piston rod when approaching the respective end of said cylinder, and means associated with said rod and responsive to the admittance of pressure fluid through one of said ports for shifting said rod and for admitting pressure fluid to one end of said piston, thereby initiating movement of said piston and subsequently causing the latter progressively to cover up the metering ports adjacent the other piston for slowing down the piston movement. I

14. In a cushioning device, a cylinder adapted to receive fluid means, outlet conduit, means adapted directly to be connected with said cylinder, a fluid operable reciprocable member operable to expel fluid from said cylinder through said outlet conduit means, and a control memberoperable by fluid pressure independently of said 15. In a cushioning device, a cylinder having an outlet opening and being adapted to receive double-acting fluid means, a fluid operable reciprocable member movable to expel fluid from said cylinder through said outlet opening, and a fluid operable control member extending into said reciprocable member and being movable independently thereof, said control member having a pas sageway therein for the admission of pressure fluid to said reciprocable member for operating the same, and means associated with said reciprocable member and adapted in response to movement of said reciprocable member, gradually to decrease the efiective discharge area of said passageway for gradually reducing'the flow of fluid therethrough, thereby slowing down the movement of said reciprocable member. i

16. In a cushioning device, a cylinder having an outlet opening and being adapted to receive fluid means, a fluid operable reciprocable member operable to expel fluid from said cylinder through said outlet opening, a fluid pressure responsive in response to fluid pressure acting upon said reciprocable member and being provided with,

reciproca-ble member to reduce the effective area of said passageway for slowing 'down the movement of said reciprocable member, said control member having two opposed piston areas for selectively moving said control member in one or the other direction in response to fluid pressure acting upon one or the other piston area.

'I'HAD. L. F 

